Accelerating Ru0/Ru4+ Adjacent Dual Sites Construction by Copper Switch for Efficient Alkaline Hydrogen Evolution

The alkaline hydrogen evolution reaction (HER) always needs the nearby dual sites of water adsorption and H-2 generation, and Ruthenium-based electrocatalysts are promising alternatives to platinum-based materials. However, achieving both high efficiency and long-term stability in the construction of the dual sites is still challenging. Herein, Cu-doped RuO2 (Cu-RuO2) is reported and undergoes instant activation for Ru-0 production at the low potential state preceding the HER. The Cu2+ ions are demonstrated to work as the switch for obtaining the activated sample of Cu-RuO2-AC, which possesses the Ru-RuO2 structure. The sample of Cu-RuO2-AC gives an overpotential of only 19 mV at the current density of 10 mA cm(-2) with a Tafel slope of 32.8 mV dec(-1). Moreover, at the mass activity of 1 A mg(Ru)(-1), it only needs 88 mV, which is lower than the 343 mV of commercial 40% Ru/C, or the 154 mV of activated bare RuO2 (RuO2-AC). Density functional theory (DFT) calculations reveal that Cu2+ doping activates the nearby Ru4+. A two-electrode H-cell device of Cu-RuO2-AC||Cu-RuO2 needs only 1.66 and 1.78 V versus RHE to achieve a current density of 100 and 200 mA cm(-2) of overall water splitting. This research can help design more efficient dual-site HER electrocatalysts.